I don't know about the other formats, but if you import 3ds to MED,
it always creates a seam of vertices that unweld.

It's not always noticeable though. Whenever I import 3ds, the FIRST thing I do
is select all the vertices (the whole model) and click the 'merge' button.

This will fix it, and you'll see which vertices were effected.
I also don't know if this continues to be a problem with A7 or not.

If the model is too small or some vertices are too close together and they merge
together in places you don't want them to, just scale the whole model larger first so it only affects the crucial vertices.

- Jason